Depending on the range of distances involved, various different physical principles are employed for electrically or electronically measuring linear distance to an object. An example is the reflection of radio waves (RADAR) or light from objects at long ranges of a few hundred meters or more. Medium range position measurements down to maybe one meter can be made by reflection of ultrasound from the object, for example. Short-range measurements of distances below one meter employ a wide variety of inductive, capacitive and resistive distance transducers.
In short-range measurement of the position of an object it is typical for the object to carry an element which is part of a transducer arrangement, or to be physically connected with the transducer. For example, a reciprocating machine part may be connected to the slider of a linear potentiometer or carry an inductive coil which forms part of a moving-coil distance transducer.
It is an object of the present invention to provide a novel position sensor which has advantages of simplicity, long-term stability and durability.